Electric accumulator.



electrolyte.

UNITED STATES ALBERT SGHMIDT-PREDARI, OF WEIMAR, GERMANY.

I ELECTRIC ACCU M U LATO R.

SPEGIFICATION'forming part of Letters Patent No. 724,619, dated April'7, 1903.

Application filed July 24, 1902. Serial No. 116,876- (No model.)

To aZZ whom, it; may concern:

Be it known that I, ALBERT SCHMIDT-PRE- DARI, engineer, a subject'of theGerman Emperor, and a resident of Weimar, in the Grand Duchy of Saxony,German Empire, have invented new and useful Improvements in ElectricAccumulators, of which the following is a full, clear, and exactspecification.

The object of my invention is an accumulator of higher capacity andhaving a longer life than those of like size and weight at present onthe market and in which, moreover, the electrolyte is less liable tosegregation, the efficiency is greater and the cost of producing theplates is less.

My invention consists in providing special active masses for both thenegative-pole electrodes and the positive-pole electrodes. Theelectrodes thus obtained may be formed and used with the usualelectrolytes; but I prefer to form the electrodes and to use the formedelectrodes with special electrolytes likewise forming parts of myinvention.

The active mass I use for the negativepole electrodes is composed of amixture of lead oxid, red lead, calcium hydroxid, and alkalithiosulfate. These additions are made for the purpose of preventing theactive mass from being hardened when brought into the formationelectrolyte. Consequently the electrodes can sustain the action of thecurrent without bursting or undergoing a deformation and the capacity isincreased. In carrying out my invention I have found, for instance,thefollowing proportions to give good results, the parts being by weight:Two parts of lead oXid, one part of red lead, onetwentieth part ofcalcium hydroxid, and onetwentieth part of sodium thiosulfate.

The active mass I use for the positivepole electrodes is composed of amixture of lead oxid, red lead, and porous spongy lead. The addition ofspongy lead is made for the purpose of giving the mass a certaintenacity and cohesion and of preventing it from being hardened whenbrought into the formation In this way also the positivepole electrodesare prevented from being deformed during the formation. out my inventionI have found, for instance, the following proportions to give goodrerial.

In carrying sults, the parts being by weight: One part of lead oxid, twoparts of red lead, and about onetwentieth part of spongy lead. Thespongy lead referred to is preferably prepared galvanically by immersingseveral plates of lead in a solution of alkali thiosulfate, preferably asolution of sodium thiosulfate of, for instance, from one andsevenhundredths (1.07) to one and twelvehundredths (1.12) specificgravity, and passing an electric current. This method has the advantagethat the spongy lead is not deposited on the plates, but is precipitatedin the liquid and collects on the bottom of the vessel.

The active masses obtained, as above set forth, are stirred up with asuitable binding material to a magma which can be kneaded and thenapplied to the plates in the usual manner. Dilute sulfuric acid of aboutone and twelve-hundredths (1.12) specific gravity is speciallyadvantageous as a binding mate- The plates, which differ in formaccording to the purpose for which the accumulator is destined, are castfrom lead in the usual manner. Before the active mass is applied to themthey are immersed in a solution of saltfor instance, of about one andfour-hundredths (1.04) specific gravity-to purify them from fattymatter. The plates made in this manner may be formed in the usual way;but, as above mentioned, I prefer to form them in a solution of Glaubersalt, which is heated before use, care being taken that no evaporationof water occurs, and is poured into the vessel while warm. found asuitable concentration of the solution to be, for instance, that at aspecific gravity of one and nine-hundredths, (1.09.)

The temperature of the liquid when poured into the vessels is preferablyof from 25 to 30 centigrade and decreases down to the surroundingtemperature during the formation, which requires from two to threehours. The formed plates may be used with the usual electrolytes; butthe electrolyte best fitted for use with them is sulfuric acid to whichan alkali thiosulfate has been added. Sulfuric acid of one andfourteen-hundredths (1.14) specific gravity with an addition ofsodium-thiosulfate solution of one and fourhundredths (1.04) specificgravity has been found to be suitable, the proportions being,

I have preferably, two volumes of sulfuric acid and from one-half to onevolume of sodium-thiosulfate solution. This liquid, which is at firstturbid, becomes clear when the accumulator is first charged and thenremains clear.

The loss by evaporation during the use of the accumulator need be madegood only with water.

It is to be understood that I do not limit myself to the figuresindicated above, which may be varied within rather large limits withoutdeparting from the scope of my invention.

Now what I claim is 1. An electric accumulator, consisting of leadplates, a magma applied tothe negativepole electrode and composed of amixture of lead oxid, red lead, calcium hydroxid, alkali thiosulfate anda suitable binding material, a magma for the positive-pole electrode,composed of a mixture of lead oxid, red lead, porous spongy lead and asuitable binding material, and a suitable electrolyte in which saidplates are immersed after formation, substantially as set forth.

2. An electric accumulator, consisting of lead plates, at magma appliedto the negativepole electrode and composed of a mixture of lead oxid,red lead, calcium hydroxid, alkali thiosulfate and a suitable bindingmaterial, a magma for the positive-pole electrode, composed of a mixtureof lead oxid, red lead, porous spongy lead and a suitable bindingmaterial, and an electrolyte composed of a mixture of sulfuric acid andalkali thiosulfate in which the plates are immersed after formation,substantially as set forth.

3. An electric accumulator-plate, consisting of a lead plate and a magmafor the negative-pole electrode, composed of a mixture of lead oxid, redlead, calcium hydroxid, alkali thiosulfate and a suitable bindingmaterial, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two subscribing witnesses.

ALBERT SOIIMIDT-PREDARI.

W'itn esses:

WOLDEMAR HAUPT, HENRY HASPER.

